The present invention relates to semiconductor devices and methods of manufacturing semiconductor devices. The present invention has particular applicability to double-gate devices.
The escalating requirements for high density and performance associated with ultra large scale integration semiconductor devices require design features, such as gate lengths, below 100 nanometers (nm), high reliability and increased manufacturing throughput. The reduction of design features below 100 nm challenges the limitations of conventional methodology.
For example, when the gate length of conventional planar metal oxide semiconductor field effect transistors (MOSFETs) is scaled below 100 nm, problems associated with short channel effects, such as excessive leakage between the source and drain, become increasingly difficult to overcome. In addition, mobility degradation and a number of process issues also make it difficult to scale conventional MOSFETs to include increasingly smaller device features. New device structures are therefore being explored to improve FET performance and allow further device scaling.
Double-gate MOSFETs represent new structures that have been considered as candidates for succeeding existing planar MOSFETs. In several respects, the double-gate MOSFETs offer better characteristics than the conventional bulk silicon MOSFETs. These improvements arise because the double-gate MOSFET has a gate electrode on both sides of the channel, rather than only on one side as in conventional MOSFETs. When there are two gates, the electric field generated by the drain is better screened from the source end of the channel. Also, two gates can control roughly twice as much current as a single gate, resulting in a stronger switching signal.
A FinFET is a recent double-gate structure that exhibits good short channel behavior. A FinFET includes a channel formed in a vertical fin. The FinFET structure may be fabricated using layout and process techniques similar to those used for conventional planar MOSFETs.
Implementations consistent with the present invention provide a method of forming a FinFET device that improves a critical dimension (CD) of the gate. The gate material may be planarized before gate patterning. In addition, an antireflective coating may be formed on the planarized gate material.
Additional advantages and other features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The advantages and features of the invention may be realized and obtained as particularly pointed out in the appended claims.
According to the present invention, the foregoing and other advantages are achieved in part by a method of manufacturing a semiconductor device that includes forming a fin structure on an insulator. The fin structure may include side surfaces and a top surface. The method may also include depositing a gate material over the fin structure and planarizing the deposited gate material. An antireflective coating may be deposited on the planarized gate material, and a gate structure may be formed out of the planarized gate material using the antireflective coating.
According to another aspect of the invention, a method of manufacturing a semiconductor device may include forming a fin structure on an insulator and depositing polysilicon over the fin structure. The method may also include polishing the polysilicon to obtain a planar top surface and depositing an antireflective layer on the planar top surface of the polysilicon. A gate structure may be formed out of the polysilicon using the antireflective layer.
According to a further aspect of the invention, a method of manufacturing a semiconductor device may include forming a fin structure on an insulator and depositing polysilicon over the fin structure. The method may also include polishing the polysilicon to obtain a planar top surface and depositing an antireflective coating on the planar top surface of the polysilicon. The method may further include depositing a photoresist layer over the antireflective coating and patterning the photoresist layer to define a gate structure. The polysilicon may be etched from around the defined gate structure.
Other advantages and features of the present invention will become readily apparent to those skilled in this art from the following detailed description. The embodiments shown and described provide illustration of the best mode contemplated for carrying out the invention. The invention is capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings are to be regarded as illustrative in nature, and not as restrictive.